differential manchester encoding (DME)
Differential Manchester Encoding (DME) or Conditioonal Diphase(CDP) is used in token ring networks and 10 Gigabit Ethernet ( 10GbE) and is specified in IEEE 802.5.
With differential Manchester coding, the state changes in the middle of each bit. The transition direction always changes at a logical "1", namely from Hi to Low. With a logical "0" the level changecorresponds to that of the clock signal. Differential Manchester coding results from XORing the clock signal and an NRZ-I codedsignal, Non Return to Zero Inverted (NRZ-I).
In 10GbE, DME coding operates at 312.5 MBaud, or a clock speed of 6.4 ns, during autonegotiation. The coding state changes each time in the middle of a bitcell with a 1-state. If the bit cell corresponds to a "0", then there is no level change in the differential Manchester coding used in 10- gigabit Ethernet, the "0" is represented by a logical Hi level. DME coded signals have a balanced DC level.